.TH std::basic_ispanstream::span 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::basic_ispanstream::span \- std::basic_ispanstream::span

.SH Synopsis
   std::span<const CharT> span() const noexcept; \fB(1)\fP (since C++23)
   void span( std::span<CharT> s ) noexcept;     \fB(2)\fP (since C++23)
   template< class SpanLike >                    \fB(3)\fP (since C++23)
   void span( SpanLike&& r ) noexcept;

   1) Gets a span referencing the written area if std::ios_base::out is set in the open
   mode of the wrapped std::basic_spanbuf, or a span referencing the underlying buffer
   otherwise.
   2) Makes the wrapped std::basic_spanbuf perform I/O on the buffer referenced by s.
   3) Same as \fB(2)\fP, except that s is obtained as if by
   std::span<const CharT> cs{std::forward<SpanLike>(r)};
   std::span<CharT> s{const_cast<CharT*>(cs.data()), cs.size()};
   . This overload participates in overload resolution only if SpanLike models
   borrowed_range, std::convertible_to<SpanLike, std::span<CharT>> is false, and
   std::convertible_to<SpanLike, std::span<const CharT>> is true.

.SH Parameters

   s - std::span referencing the storage to be use as the new underlying buffer of
       stream
   r - borrowed_range to be use as the new underlying buffer of stream

.SH Return value

   1) A std::span referencing the underlying buffer or written area, depending on the
   open mode of the wrapped std::basic_spanbuf.
   2,3) \fI(none)\fP

.SH Example


// Run this code

 #include <cassert>
 #include <iostream>
 #include <span>
 #include <spanstream>

 int main()
 {
     char out_buf[16];
     std::ospanstream ost{std::span<char>{out_buf}};
     ost << "C++" << ' ' << 23 << '\\0'; // note explicit null-termination
     auto sp = ost.span();
     assert(
         sp[0] == 'C' && sp[1] == '+' && sp[2] == '+' &&
         sp[3] == ' ' && sp[4] == '2' && sp[5] == '3' &&
         sp[6] == '\\0'
     );
     std::cout << "sp.data(): [" << sp.data() << "]\\n";
     std::cout << "out_buf: [" << out_buf << "]\\n";
     // spanstream uses out_buf as internal storage, no allocations
     assert(static_cast<char*>(out_buf) == sp.data());

     const char in_buf[] = "X Y 42";
     std::ispanstream ist{std::span<const char>{in_buf}};
     assert(static_cast<const char*>(in_buf) == ist.span().data());
     char c;
     ist >> c;
     assert(c == 'X');
     ist >> c;
     assert(c == 'Y');
     int i;
     ist >> i;
     assert(i == 42);
     ist >> i; // buffer is exhausted
     assert(!ist);
 }

.SH Output:

 sp.data(): [C++ 23]
 out_buf: [C++ 23]

.SH See also

   span    obtains or initializes an underlying buffer according to mode
   (C++23) \fI(public member function of std::basic_spanbuf<CharT,Traits>)\fP
